A non-contact 3D combining method employed for a conventional vision measuring system may be classified into the provision of a combined three-dimensional shape by focal position detection (Point From Focus; hereinafter referred to as PFF) and the provision of a combined three-dimensional shape by white light interference (hereafter referred to as WLI). Both the methods provides a combined three-dimensional shape on the basis of successive images, captured while the measuring head is being scanned in the direction of an optical axis (images referred to here are frame images), and the information on the position at which the images are acquired.
Here, when an interlace camera is used to capture successive images, as illustrated by way of example in FIG. 1 STEP (1), since an image within the range of one field of view is separately captured in two fields, i.e., odd and even fields, the interlace camera mounted on a measuring head 10 to be scanned in the Z axis direction needs to combine the Odd and Even field images into an image of one field of view (frame image) in order to acquire a combined three-dimensional shape.
As shown in FIG. 1 STEP (1), for example, for Odd and Even field images (raw images) captured at positions Z2 and Z3, the frame image combining process produces interpolation images of the Even and Odd fields at the same respective positions Z2 and Z3 (interpolation field images) as shown in FIG. 1 STEP (2), and then combines the raw images at the positions Z2 and Z3 (Odd at Z2 and Even at Z3) with the respective interpolation field images (Even at Z2 and Odd at Z3), thereby generating the frame images at the respective positions Z2 and Z3 as shown in FIG. 1 STEP (3).